Giant Easter Island 'Hats' Rolled Into Place, Study Says

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SAN FRANCISCO — The distinctive headgear worn by some of the
famous Easter Island statues may have been rolled up ramps to
reach those high perches, a new study suggests.

A simple analysis of the physics suggests that rolling the
headwear — bulky cylindrical shapes that look like Russian fur
hats — would have been a relatively easy matter, said study
co-author Sean Hixon, an undergraduate student in archaeology and
geology at the University of Oregon, who presented his findings
here on April 16 at the 80th Annual Meeting of the Society for
American Archaeology.

In addition, other features, such as indentations at the bases of
the hats, line up with the rolling theory of placement, Hixon
said.

Easter Island hats

Since Europeans arrived at the location in the 1700s, people have
wondered how the residents of Easter Island, or Rapa Nui, off the
coast of Chile, raised their majestic statues. Some scientists
have speculated that the
statues were walked into place. Others have argued that the
native islanders chopped down the island's forests to roll the
stone behemoths across the landscape, leading to environmental
devastation and the collapse of the Easter Island civilization.

Some of these Easter
Island statues, or moai, are topped by large red headgear.
About 100 of these "hats," made from red volcanic rock called
scoria, have been found, with many strewn along ancient paths on
the island.

Historians and ethnographers proposed that these "hats" were
everything from feathered diadems, to turbans, to wigs, to
elaborate hairdos. Nowadays, most scholars think the ornaments
were meant to represent hair, and the
Rapa Nui word for them, "pukao," means topknot, Hixon said.
The pukaos for the biggest statues could be roughly 6.5 feet (2
meters) in diameter and weigh 12 tons, he added.

No one knows exactly what the hats signified, though their red
color suggests they may have had a ritual significance, Hixon
said. Because the hats were carved separately, archaeologists
have questioned how people got the ornaments atop the moai, as
the biggest of the statues could weigh 75 tons and stand a
staggering 40 feet (12 meters) high.

Rolling, rolling, rolling

Hixon and his colleagues used simple physics to model the force
and torque required to place the pukao atop the moai via
different techniques, such as rolling the objects up a ramp to
the top of the statues, building a giant tower and using a
pulley system, or erecting the pukao and moai simultaneously.

The mostly oblong cross-section of the pukao meant that rolling
up a ramp would have taken relatively little energy, and could
have been done with fewer than 10 people, Hixon found. The oblong
shape would have an advantage over a circular cross-section: it
would prevent the pukao from rolling down the ramp by accident,
HIxon said.

In addition, many of the statues have a small lip at the base.
These indentations are about 0.78 inches (2 centimeters) thick,
and "they pretty much fit the
heads of the moai," Hixon told Live Science.

"The base indentation isn't really necessary for the hat once
it's on the statue. The hats are pretty massive. It's not like
they're going to fall off without the base indentation," Hixon
said. Instead, these indentations might have helped prevent the
pukao from tipping over during placement, if the statues
themselves happened to tilt forward a bit, Hixon said.

Many of the pukao also exhibit ring-shaped indentations and
vertical scratches around the sides, which could have provided
traction as the headgear was rolled up a ramp, Hixon said.

Still, the research is far from definitive. Any of the proposed
methods for raising the hats are theoretically possible with
enough people, Hixon said. And erosion and damage have altered
the sides of the pukaos, so it's difficult to determine whether
the scratches on the outer surface were deliberately placed,
Hixon said.